Many space and terrestrial devices are powered by solar energy generated from an array of photovoltaic cells. In these applications, the electrical power available from the solar array is dependent on a variety of factors including temperature, illumination available, the number of solar cells in the array and many other array properties. Given this sometimes unpredictable fluctuation of electrical energy, control of the electrical power from the solar array is essential for efficient operation of those applications that utilize solar power. Many developments in electrical power control systems for solar arrays have concentrated upon determining the peak power available from the solar array and applying that peak power when there is adequate load and battery demand.
Such peak power control systems generally utilize a variety of techniques to ascertain the maximum power available from the solar array. In particular, some peak power control systems determine the maximum power available from the solar array to constantly apply that peak power to a load. One system for determining the maximum power available from the solar array detects the current and voltage at either the load or the solar array to calculate the power value, which is used to define the operating point of the solar array. Subsequently, the operating point of the solar array is moved a small amount and a new power setting is compared to the previous power setting. If the power measured at the new setting is larger, the solar array operating point is moved again in the same direction. This iterative process is repeated until the new power operating point is lower than the previous operating point. At that time, the operating point is moved in the opposite direction until the power drops again. This operation for obtaining the peak power from the solar array is known as dithering. Another system for obtaining the peak power from a solar array attempts to approximate the peak power available from the solar array by utilizing an assumed characteristic of the solar array. In such systems, the voltage maximizing the power output is assumed to be constant or linearly related to the current. For peak power control, the current value is sampled and an input to a voltage reference circuit determines how the solar array output should be adjusted to obtain the maximum power.
As such, some devices for controlling electrical power from solar arrays seek, at all times, to deliver to loads the maximum power available from the solar array. Yet, given the load demand on the solar array, a constant delivery of maximum power may not be the most efficient utilization of the power available from the solar array nor the most effective manner to protect the battery power source. In addition, many existing peak power trackers are not designed for wide voltage changes that are output from the solar array such as voltage changes that occur while a system is in low earth orbit.